uv coordinates to xyz

Hi,

I am trying to trace coordinates on a surface of a 3d object.

Let' s say I start with a jit.gl.mesh geometry data describing the object. One idea to achieve this would be to to sample points on a 2d uv surface and receive xyz coordinates of corresponding point. What would be the correct approach to achieve this in Jitter? It seems that jit.gl.shader object has access to this data, but can it report back to the max environemnt?

Any hints would be great!